Smoking substitute apparatus

ABSTRACT

A smoking substitute apparatus for generating an aerosol, comprising: an aerosol generation chamber containing an aerosol generator being operable to generate an aerosol from an aerosol precursor, the aerosol generation chamber having a chamber outlet and at least one chamber inlet, air flowing in use from said at least one chamber inlet into the aerosol generation chamber towards the chamber outlet to entrain generated aerosol for inhalation by a user drawing on the apparatus; wherein, when the apparatus is oriented upright, said at least one chamber inlet is positioned higher than the position of the aerosol generator and configured so that substantially all of the airflow entering the aerosol generation chamber is directed away from the aerosol generator.

CROSS-REFERENCE TO RELATED APPLICATIONS/INCORPORATION BY REFERENCESTATEMENT

This application is a non-provisional application claiming benefit tothe international application no. PCT/EP2020/076261 filed on Sep. 21,2020, which claims priority to EP 19198651.2 filed on Sep. 20, 2019. Theentire contents of each of the above-referenced applications are herebyincorporated herein by reference in their entirety.

FIELD OF THE DISCLOSURE

The present disclosure relates to a smoking substitute apparatus and, inparticular, a smoking substitute apparatus that is able to reduce fluidleakage during use, as well as to deliver nicotine to a user in aneffective manner.

BACKGROUND

The smoking of tobacco is generally considered to expose a smoker topotentially harmful substances. It is thought that a significant amountof the potentially harmful substances are generated through the burningand/or combustion of the tobacco and the constituents of the burnttobacco in the tobacco smoke itself.

Low temperature combustion of organic material such as tobacco is knownto produce tar and other potentially harmful by-products. There havebeen proposed various smoking substitute systems in which theconventional smoking of tobacco is avoided.

Such smoking substitute systems can form part of nicotine replacementtherapies aimed at people who wish to stop smoking and overcome adependence on nicotine.

Known smoking substitute systems include electronic systems that permita user to simulate the act of smoking by producing an aerosol (alsoreferred to as a “vapor”) that is drawn into the lungs through the mouth(inhaled) and then exhaled. The inhaled aerosol typically bears nicotineand/or a flavorant without, or with fewer of, the health risksassociated with conventional smoking.

In general, smoking substitute systems are intended to provide asubstitute for the rituals of smoking, whilst providing the user with asimilar, or improved, experience and satisfaction to those experiencedwith conventional smoking and with combustible tobacco products.

The popularity and use of smoking substitute systems has grown rapidlyin the past few years. Although originally marketed as an aid to assisthabitual smokers wishing to quit tobacco smoking, consumers areincreasingly viewing smoking substitute systems as desirable lifestyleaccessories. There are a number of different categories of smokingsubstitute systems, each utilizing a different smoking substituteapproach. Some smoking substitute systems are designed to resemble aconventional cigarette and are cylindrical in form with a mouthpiece atone end. Other smoking substitute devices do not generally resemble acigarette (for example, the smoking substitute device may have agenerally box-like form, in whole or in part).

One approach is the so-called “vaping” approach, in which a vaporizableliquid, or an aerosol precursor or aerosol precursor, sometimestypically referred to herein as “e-liquid”, is heated by a heatingdevice (sometimes referred to herein as an electronic cigarette or“e-cigarette” device) to produce an aerosol vapor which is inhaled by auser. The e-liquid typically includes a base liquid, nicotine and mayinclude a flavorant. The resulting vapor therefore also typicallycontains nicotine and/or a flavorant. The base liquid may includepropylene glycol and/or vegetable glycerin.

A typical e-cigarette device includes a mouthpiece, a power source(typically a battery), a tank for containing e-liquid and a heatingdevice. In use, electrical energy is supplied from the power source tothe heating device, which heats the e-liquid to produce an aerosol (or“vapor”) which is inhaled by a user through the mouthpiece.

E-cigarettes can be configured in a variety of ways. For example, thereare “closed system” vaping smoking substitute systems, which typicallyhave a sealed tank and heating element. The tank is pre-filled withe-liquid and is not intended to be refilled by an end user. One subsetof closed system vaping smoking substitute systems include a main bodywhich includes the power source, wherein the main body is configured tobe physically and electrically couplable to a consumable including thetank and the heating element. In this way, when the tank of a consumablehas been emptied of e-liquid, that consumable is removed from the mainbody and disposed of. The main body can then be reused by connecting itto a new, replacement, consumable. Another subset of closed systemvaping smoking substitute systems are completely disposable, andintended for one-use only.

There are also “open system” vaping smoking substitute systems whichtypically have a tank that is configured to be refilled by a user. Inthis way the entire device can be used multiple times.

An example vaping smoking substitute system is the myblu™ e-cigarette.The myblu™ e-cigarette is a closed system which includes a main body anda consumable. The main body and consumable are physically andelectrically coupled together by pushing the consumable into the mainbody. The main body includes a rechargeable battery. The consumableincludes a mouthpiece and a sealed tank which contains e-liquid. Theconsumable has an inlet which is fluidly connected to an outlet at themouthpiece by an air flow channel. The consumable further includes aheater, which for this device is a heating filament coiled around aportion of a wick positioned across the width of the air flow passage.The wick is partially immersed in the e-liquid, and conveys e-liquidfrom the tank to the heating filament. The system is controlled by amicroprocessor on board the main body. The system includes a sensor fordetecting when a user is inhaling through the mouthpiece, themicroprocessor then activating the device in response. When the systemis activated, electrical energy is supplied from the power source to theheating device, which heats e-liquid from the tank to produce a vapor,which promptly condenses to form an aerosol as it is cooled by an airflow passing through the air flow passage. A user may therefore inhalethe generated aerosol through the mouthpiece.

SUMMARY OF THE DISCLOSURE

For a smoking substitute system, it is desirable to deliver nicotineinto the user's lungs, where it can be absorbed into the bloodstream.However, the present disclosure is based in part on a realization thatsome prior art smoking substitute systems, such delivery of nicotine isnot efficient. In some prior art systems, the aerosol droplets have asize distribution that is not suitable for delivering nicotine to thelungs. Aerosol droplets of a large particle size tend to be deposited inthe mouth and/or upper respiratory tract. Aerosol particles of a small(e.g., sub-micron) particle size can be inhaled into the lungs but maybe exhaled without delivering nicotine to the lungs. As a result, theuser would require drawing a longer puff, more puffs, or vaporizinge-liquid with a higher nicotine concentration in order to achieve thedesired experience.

Furthermore, in such prior art smoking substitute systems the air inletis often positioned at the base of the vaporizing chamber. In use,coalesced aerosol droplets that are too large to be suspended in theairflow, as well as excess aerosol precursor that is wicked from thesealed tank, may undesirably leak through the air inlet by gravity.

Accordingly, there is a need for improvement in the delivery of nicotineto a user, as well as reduction in fluid leakage, in the context of asmoking substitute system.

The present disclosure has been devised in the light of the aboveconsiderations.

In a general aspect, the present disclosure relates to a smokingsubstitute apparatus that, when placed in an upright orientation, has atleast one chamber inlet positioned above the aerosol generator in anaerosol generation chamber. As such, substantially all of the air flowentering the aerosol generation chamber is directed away from theaerosol generator.

According to a first preferred aspect there is provided a smokingsubstitute apparatus for generating an aerosol, comprising:

an aerosol generation chamber containing an aerosol generator beingoperable to generate an aerosol from an aerosol precursor, the aerosolgeneration chamber having a chamber outlet and at least one chamberinlet, air flowing in use from the at least one chamber inlet into theaerosol generation chamber towards the chamber outlet to entraingenerated aerosol for inhalation by a user drawing on the apparatus;

wherein, when the apparatus is oriented upright, said at least onechamber inlet is positioned higher than the position of the aerosolgenerator and configured so that substantially all of the airflowentering the aerosol generation chamber is directed away from theaerosol generator.

The aerosol generation chamber may be provided at or towards a first endof a housing of the apparatus. For example, the base of the aerosolgeneration chamber may form the base of the housing. Said first end ofthe housing may be engageable with a main body of a smoking substitutesystem. The chamber outlet may open towards the second end of thehousing and in fluid communication with an outlet at a mouthpiece at thesecond end of the housing, onto which the user may puff in order to drawan air flow through the aerosol generation chamber.

For the avoidance of doubt, we note here that a user may draw on theapparatus with or without making physical contact with the apparatus.For example, a mouthpiece or other intervening structure may beprovided, separate from and/or separable from the housing of the smokingsubstitute apparatus, and the user's lips may make contact with thismouthpiece or other intervening structure when drawing on the apparatus.

For convenience of discussion of the structure of the smoking substituteapparatus, it is considered to be placed in an upright orientation. Incontrast to prior art smoking substitute systems, which generate anaerosol by directly passing an air flow over the heater, the at leastone chamber inlet according to the present disclosure may be located ata position above the aerosol generator in said upright orientation. Inother words, the chamber inlet may be positioned downstream to theaerosol generator in the direction of aerosol flow. For example,substantially all of the air flow may enter the aerosol generationchamber along an air flow path between the at least one chamber inletand the chamber outlet, and wherein the aerosol generator may bearranged to be spaced from the air flow path. More specifically, the atleast one chamber inlet may open, at the aerosol generation chamber, ina direction away from the aerosol generator, e.g., the at least onechamber inlet may open in a direction parallel to the aerosol generator.Advantageously, such arrangement may avoid having the majority of airflow directly impinging upon the aerosol generator, and therefore it mayreduce the amount of turbulence in the vicinity of the aerosolgenerator. As a result, an aerosol with enlarged droplet sizes may beformed.

The aerosol precursor may comprise a liquid aerosol precursor, andwherein the aerosol generator may comprise a heater configured togenerate the aerosol by vaporizing the liquid aerosol precursor. Theliquid aerosol precursor may be an e-liquid and may comprise nicotineand a base liquid such as propylene glycol and/or vegetable glycerin andmay include a flavorant. The aerosol generator may be a heater such as aheater coil wound around a wick.

In use, the aerosol generator may vaporize the aerosol precursor to forma vapor. The vapor may expand or flow from the aerosol generator tomerge or entrain into the air flow entering the chamber through the atleast one chamber inlet. For example, the formation of vapor mayincrease the internal pressure at the aerosol generation chamber, andmay advantageously aid the convection of the vapor towards the chamberoutlet. Said vapor may cool and condense to from an aerosol in theaerosol generation chamber and subsequently be discharged towards thechamber outlet. More specifically, substantially all of the air flowentering the aerosol generation chamber may not directly pass over theaerosol generator but may only come into contact with the vapor and/oraerosol once it is formed. Even though the air flow may induce a degreeof turbulence in the aerosol generation chamber, the turbulence in thevicinity of the aerosol generator in the present disclosure issignificantly lower than the amount of turbulence that would otherwiseoccur in prior art consumables. The base of the aerosol generationchamber may be sealed against air flow. This is discussed in more detailbelow.

Optionally, when the apparatus is oriented upright, the aerosolgeneration chamber is sealed against air flow into or out of the chamberin a region level with and below the position of the aerosol generator.For example, in said upright orientation the chamber outlet of theaerosol generation chamber may face an upward direction, with the sealedregion of the aerosol generation chamber positioned below both thechamber inlet and chamber outlet. That is, in the sealed region of theaerosol generation chamber may be free from apertures that allow thepassage of an air flow. The sealed region of the aerosol generationchamber may comprise sealed apertures for allowing electrical contact toextending therethrough. As a result, any excess aerosol precursoraccumulated at the aerosol generator, e.g., in the case of a heater, ata wick of the heater, may be retained in the aerosol generation chamberby gravity. Therefore advantageously, such arrangement may reduce oreliminate liquid leakage through the smoking substitute apparatus.

In alternative arrangements, some air flow may be permitted to enter theaerosol generation chamber. However, where such air flow is permitted,preferably this is only in an amount that does not significantly affectthe degree of turbulence around the aerosol generator.

Optionally, the chamber inlet may form on a sidewall of the aerosolgeneration chamber at a position in between the aerosol generator andthe chamber outlet. In some embodiments, at least a portion of thesidewall of the aerosol generation chamber may be defined by thehousing, and wherein the chamber inlet may form on said portion ofsidewall through the housing. For example, the chamber inlet may open ona sidewall of the housing and into the aerosol generation chamber. Inother embodiments, the aerosol generation chamber may form separately tothe housing. For example, the aerosol generation chamber may extendcoaxially with the housing, and an annulus may be defined between therespective sidewalls of the aerosol generation chamber and the housing.The annulus may comprise a tank for storing a reservoir of aerosolprecursor. In such embodiments, an air inlet passage may extend from anopening of the sidewall of the housing, through the annulus to thechamber inlet of the aerosol generation chamber.

Optionally, the smoking substitute apparatus is configured to generatean aerosol having a droplet size, d₅₀, of at least 1 μm. Optionally, thesmoking substitute apparatus is configured to generate an aerosol havinga droplet size, d₅₀, ranged between 1 μm to 4 μm. Optionally, thesmoking substitute apparatus is configured to generate an aerosol havinga droplet size, d₅₀, ranged between 2 μm to 3 μm. Advantageously,aerosol having droplets in such size ranges may improve delivery ofnicotine into the user's lung, by reducing the likelihood of nicotinedeposition in the mouth and/or upper respiratory tract, e.g., in thecase of oversized aerosol droplets, or not being absorbed at all, e.g.,in the case of undersized aerosol droplets.

Optionally, the aerosol generator is adjacent to the base of the aerosolgeneration chamber. Advantageously, such arrangement may allow theaerosol generator to be located at a position furthest away from thechamber inlet and the air flow entering therethrough, and therefore itmay limit the turbulence in the vicinity of the aerosol generator.Further, such arrangement may increase the residence time of the vaporin the aerosol generation chamber and thus it may allow some aerosoldroplets to form and even coalesce before being entrained in the airflow. Additionally in the case of a heater, at such location, the wickof the heater may absorb excess aerosol precursor that is collected atthe base of aerosol generation chamber, and subsequently allowing it tobe vaporized.

Alternatively, the aerosol generator is located at a position adjacentto the chamber inlet, e.g., the aerosol generator is immediatelyupstream of the chamber inlet. Advantageously, this may shorten the pathof travel for the aerosol and thereby allow the aerosol to be promptlyentrained or merged into the air flow.

Optionally, the aerosol generation chamber is configured to have asubstantially uniform cross sectional profile along its length. Forexample, the aerosol flow path along the length of the aerosolgeneration chamber may have the same cross-sectional area.Advantageously, this may reduce turbulence, as well as fluctuation inpressure in the aerosol flow path and thereby such arrangement may leadto an increase in the size of aerosol droplets.

Optionally, the smoking substitute apparatus further comprises a housingcontaining the aerosol generation chamber, wherein one or moreelectrical contacts are provided on a first end of the housing andelectrically connected with the aerosol generator, and wherein the oneor more electrical contacts are configured to engage with correspondingelectrical terminals on a main body of a smoking substitute system. Forexample, electrical connectors may extend from the aerosol generator,through respective sealed apertures at the base of the aerosolgeneration chamber, to establish electrical connection with the one ormore electrical contacts. Advantageously, such arrangement may allowelectrical connection between the main body and the aerosol generator toestablish by biasing the housing towards the main body.

Optionally, the smoking substitute apparatus further comprises a housingcontaining the aerosol generation chamber, wherein one or moreelectrical contacts have an electrically conductive surface whichextends orthogonally to the longitudinal axis of the housing. Forexample, the electrically conductive surface may form from conductorstrips, e.g., copper strips that extends partially across the first endof the housing. Advantageously, such arrangement may increase thesurface area of the electrical contacts.

Alternatively, or in addition, one or more electrical contacts areprovided on a sidewall of the housing and electrically connected withthe aerosol generator, wherein the one or more electrical contacts areconfigured to engage with corresponding electrical terminals on a mainbody of a smoking substitute system. For example, electrical connectorsmay extend from the aerosol generator, through respective sealedapertures at the sidewalls of the aerosol generation chamber, toestablish electrical connection with the one or more electricalcontacts. Advantageously, such arrangement may allow electricalconnection between the main body and the aerosol generator to establishby sliding the housing into a cavity of the main body.

Optionally, the one or more electrical contacts have an electricallyconductive surface which is parallel to the longitudinal axis of thehousing. For example, the electrically conductive surface may form fromconductor strips, e.g., copper strips that extends along the sidewall ofthe housing. Advantageously, such arrangement may increase the surfacearea of the electrical contacts.

Optionally, the one or more electrical contacts are provided on an outersurface of the housing. For example, the electrical contacts may form onthe external surface at the base of the housing, or they may form on theexternal surface at the sidewall of the housing. Advantageously, sucharrangement may allow the one or more electrical contacts to establishconnection with corresponding electrical contacts formed on an internalsurface of a cavity of the main body.

Optionally, the one or more electrical contacts are resiliently movablefor effecting a secure electrical connection with the correspondingelectrical terminals on the main body. For example, the electricalcontacts may form an interference fit with the corresponding electricalterminals of main body, whereby such interference fit may help retainingthe housing within the main body.

The smoking substitute apparatus may be in the form of a consumable. Theconsumable may be configured for engagement with a main body. When theconsumable is engaged with the main body, the combination of theconsumable and the main body may form a smoking substitute system suchas a closed smoking substitute system. For example, the consumable maycomprise components of the system that are disposable, and the main bodymay comprise non-disposable or non-consumable components (e.g., powersupply, controller, sensor, etc.) that facilitate the generation and/ordelivery of aerosol by the consumable. In such an embodiment, theaerosol precursor (e.g., e-liquid) may be replenished by replacing aused consumable with an unused consumable.

Alternatively, the smoking substitute apparatus may be a non-consumableapparatus (e.g., that is in the form of an open smoking substitutesystem). In such embodiments an aerosol precursor (e.g., e-liquid) ofthe system may be replenished by re-filling, e.g., a reservoir of thesmoking substitute apparatus, with the aerosol precursor (rather thanreplacing a consumable component of the apparatus).

In light of this, it should be appreciated that some of the featuresdescribed herein as being part of the smoking substitute apparatus mayalternatively form part of a main body for engagement with the smokingsubstitute apparatus. This may be the case in particular when thesmoking substitute apparatus is in the form of a consumable.

Where the smoking substitute apparatus is in the form of a consumable,the main body and the consumable may be configured to be physicallycoupled together. For example, the consumable may be at least partiallyreceived in a recess of the main body, such that there is aninterference fit between the main body and the consumable.Alternatively, the main body and the consumable may be physicallycoupled together by screwing one onto the other, or through a bayonetfitting, or the like.

Thus, the smoking substitute apparatus may comprise one or moreengagement portions for engaging with a main body. In this way, one endof the smoking substitute apparatus may be coupled with the main body,whilst an opposing end of the smoking substitute apparatus may define amouthpiece of the smoking substitute system.

The smoking substitute apparatus may comprise a reservoir configured tostore an aerosol precursor, such as an e-liquid. The e-liquid may, forexample, comprise a base liquid. The e-liquid may further comprisenicotine. The base liquid may include propylene glycol and/or vegetableglycerin. The e-liquid may be substantially flavorless. That is, thee-liquid may not contain any deliberately added additional flavorant andmay consist solely of a base liquid of propylene glycol and/or vegetableglycerin and nicotine.

The reservoir may be in the form of a tank. At least a portion of thetank may be light-transmissive. For example, the tank may comprise awindow to allow a user to visually assess the quantity of e-liquid inthe tank. A housing of the smoking substitute apparatus may comprise acorresponding aperture (or slot) or window that may be aligned with alight-transmissive portion (e.g., window) of the tank. The reservoir maybe referred to as a “clearomizer” if it includes a window, or a“cartomizer” if it does not.

The smoking substitute apparatus may comprise a passage for fluid flowtherethrough. The passage may extend through (at least a portion of) thesmoking substitute apparatus, from the chamber outlet to an outlet ofthe apparatus. The outlet may be at a mouthpiece of the smokingsubstitute apparatus. The passage may be at least partially defined bythe tank. The tank may substantially (or fully) define the passage, forat least a part of the length of the passage. In this respect, the tankmay surround the passage, e.g., in an annular arrangement around thepassage.

The aerosol generator may comprise a wick. The aerosol generator mayfurther comprise a heater. The wick may comprise a porous material,capable of wicking the aerosol precursor. A portion of the wick may beexposed in the aerosol generation chamber, however said portion of thewick may be spaced from the air flow path. The wick may also compriseone or more portions in contact with liquid stored in the reservoir. Forexample, opposing ends of the wick may protrude into the reservoir andan intermediate portion (between the ends) may extend across the aerosolgeneration chamber. Thus, liquid may be drawn (e.g., by capillaryaction) along the wick, from the reservoir to the portion of the wickexposed in the aerosol generation chamber.

The heater may comprise a heating element, which may be in the form of afilament wound about the wick (e.g., the filament may extend helicallyabout the wick in a coil configuration). The heating element may bewound about the intermediate portion of the wick that is extended acrossthe aerosol generation chamber. The heating element may be electricallyconnected (or connectable) to a power source. Thus, in operation, thepower source may apply a voltage across the heating element so as toheat the heating element by resistive heating. This may cause liquidstored in the wick (i.e., drawn from the tank) to be heated so as toform a vapor in the aerosol generation chamber. This vapor maysubsequently cool to form an aerosol in the aerosol generation chamber,typically downstream from the heating element.

As a user puffs on the mouthpiece, vaporized e-liquid may be drawntowards the chamber outlet. The vapor may cool, and thereby nucleateand/or condense to form a plurality of aerosol droplets, e.g.,nicotine-containing aerosol droplets. A portion of these aerosoldroplets may be delivered to and be absorbed at a target delivery site,e.g., a user's lung, whilst a portion of the aerosol droplets mayinstead adhere onto other parts of the user's respiratory tract, e.g.,the user's oral cavity and/or throat. Typically, in some known smokingsubstitute apparatuses, the aerosol droplets as measured at the outletof the passage, e.g., at the mouthpiece, may have a droplet size, d₅₀,of less than 1 μm.

The particle droplet sizes, d₅₀, of an aerosol may be measured by alaser diffraction technique. For example, the stream of aerosol outputfrom the outlet of the passage may be drawn through a Malvern Sprayteclaser diffraction system, where the intensity and pattern of scatteredlaser light are analyzed to calculate the size and size distribution ofaerosol droplets. As will be readily understood, the particle sizedistribution may be expressed in terms of d₁₀, d⁵⁰ and d₉₀, for example.Considering a cumulative plot of the volume of the particles measured bythe laser diffraction technique, the d₁₀ particle size is the particlesize below which 10% by volume of the sample lies. The d₅₀ particle sizeis the particle size below which 50% by volume of the sample lies. Thed₉₀ particle size is the particle size below which 90% by volume of thesample lies. Unless otherwise indicated herein, the particle sizemeasurements are volume-based particle size measurements, rather thannumber-based or mass-based particle size measurements.

The smoking substitute apparatus (or main body engaged with the smokingsubstitute apparatus) may comprise a power source. The power source maybe electrically connected (or connectable) to a heater of the smokingsubstitute apparatus (e.g., when the smoking substitute apparatus isengaged with the main body). The power source may be a battery (e.g., arechargeable battery). A connector in the form of e.g., a USB port maybe provided for recharging this battery.

When the smoking substitute apparatus is in the form of a consumable,the smoking substitute apparatus may comprise an electrical interfacefor interfacing with a corresponding electrical interface of the mainbody. One or both of the electrical interfaces may include one or moreelectrical contacts. Thus, when the main body is engaged with theconsumable, the electrical interface of the main body may be configuredto transfer electrical power from the power source to a heater of theconsumable via the electrical interface of the consumable.

The electrical interface of the smoking substitute apparatus may also beused to identify the smoking substitute apparatus (in the form of aconsumable) from a list of known types. For example, the consumable mayhave a certain concentration of nicotine and the electrical interfacemay be used to identify this. The electrical interface may additionallyor alternatively be used to identify when a consumable is connected tothe main body.

Again, where the smoking substitute apparatus is in the form of aconsumable, the main body may comprise an identification means, whichmay, for example, be in the form of an RFID reader, a barcode or QR codereader. This identification means may be able to identify acharacteristic (e.g., a type) of a consumable engaged with the mainbody. In this respect, the consumable may include any one or more of anRFID chip, a barcode or QR code, or memory within which is an identifierand which can be interrogated via the identification means.

The smoking substitute apparatus or main body may comprise a controller,which may include a microprocessor. The controller may be configured tocontrol the supply of power from the power source to the heater of thesmoking substitute apparatus (e.g., via the electrical contacts). Amemory may be provided and may be operatively connected to thecontroller. The memory may include non-volatile memory. The memory mayinclude instructions which, when implemented, cause the controller toperform certain tasks or steps of a method.

The main body or smoking substitute apparatus may comprise a wirelessinterface, which may be configured to communicate wirelessly withanother device, for example a mobile device, e.g., via Bluetooth®. Tothis end, the wireless interface could include a Bluetooth® antenna.Other wireless communication interfaces, e.g., WIFI®, are also possible.The wireless interface may also be configured to communicate wirelesslywith a remote server.

A puff sensor may be provided that is configured to detect a puff (i.e.,inhalation from a user). The puff sensor may be operatively connected tothe controller so as to be able to provide a signal to the controllerthat is indicative of a puff state (i.e., puffing or not puffing). Thepuff sensor may, for example, be in the form of a pressure sensor or anacoustic sensor. That is, the controller may control power supply to theheater of the consumable in response to a puff detection by the sensor.The control may be in the form of activation of the heater in responseto a detected puff. That is, the smoking substitute apparatus may beconfigured to be activated when a puff is detected by the puff sensor.When the smoking substitute apparatus is in the form of a consumable,the puff sensor may be provided in the consumable or alternatively maybe provided in the main body.

The term “flavorant” is used to describe a compound or combination ofcompounds that provide flavor and/or aroma. For example, the flavorantmay be configured to interact with a sensory receptor of a user (such asan olfactory or taste receptor). The flavorant may include one or morevolatile substances.

The flavorant may be provided in solid or liquid form. The flavorant maybe natural or synthetic. For example, the flavorant may include menthol,licorice, chocolate, fruit flavor (including e.g., citrus, cherry etc.),vanilla, spice (e.g., ginger, cinnamon) and tobacco flavor. Theflavorant may be evenly dispersed or may be provided in isolatedlocations and/or varying concentrations.

According to a second aspect there is provided a smoking substitutesystem for generating an aerosol, comprising:

-   -   the smoking substitute apparatus of the first aspect; and a main        body configured to engage with the smoking substitute apparatus;        wherein the main body comprises a controller and a power source        configured to energize the aerosol generator.

Optionally, the main body comprises corresponding electrical terminalsconfigured to engage with the one or more electrical contacts by asliding fit. For example, the smoking substitute system may beconfigured such that electrical connections between the heater and themain body by sliding the housing into a cavity of the main body.

According to a third aspect there is provided a method of using thesmoking substitute apparatus of the first aspect, comprising: generatingan aerosol with the aerosol generator;

drawing on the apparatus to cause an air flow to enter the aerosolgeneration chamber and entrain the generated aerosol.

The present inventors consider that a flow rate of 1.3 L min⁻¹ istowards the lower end of a typical user expectation of flow rate througha conventional cigarette and therefore through a user-acceptable smokingsubstitute apparatus. The present inventors further consider that a flowrate of 2.0 L min⁻¹ is towards the higher end of a typical userexpectation of flow rate through a conventional cigarette and thereforethrough a user-acceptable smoking substitute apparatus. Embodiments ofthe present disclosure therefore provide an aerosol with advantageousparticle size characteristics across a range of flow rates of airthrough the apparatus.

The aerosol may have a Dv50 of at least 1.1 μm, at least 1.2 μm, atleast 1.3 μm, at least 1.4 μm, at least 1.5 μm, at least 1.6 μm, atleast 1.7 μm, at least 1.8 μm, at least 1.9 μm or at least 2.0 μm.

The aerosol may have a Dv50 of not more than 4.9 μm, not more than 4.8μm, not more than 4.7 μm, not more than 4.6 μm, not more than 4.5 μm,not more than 4.4 μm, not more than 4.3 μm, not more than 4.2 μm, notmore than 4.1 μm, not more than 4.0 μm, not more than 3.9 μm, not morethan 3.8 μm, not more than 3.7 μm, not more than 3.6 μm, not more than3.5 μm, not more than 3.4 μm, not more than 3.3 μm, not more than 3.2μm, not more than 3.1 μm or not more than 3.0 μm.

A particularly preferred range for Dv50 of the aerosol is in the range2-3 μm.

When the air flow rate inhaled by the user through the apparatus is 1.3L min⁻¹, the average magnitude of velocity of air in the vaporizationchamber may be not more than 0.001 ms⁻¹, or not more than 0.005 ms⁻¹, ornot more than 0.01 ms⁻¹, or not more than 0.05 ms⁻¹.

The aerosol generator may comprise a vaporizer element loaded withaerosol precursor, the vaporizer element being heatable by a heater andpresenting a vaporizer element surface to air in the vaporizationchamber. A vaporizer element region may be defined as a volume extendingoutwardly from the vaporizer element surface to a distance of 1 mm fromthe vaporizer element surface.

The air inlet, flow passage, outlet and the vaporization chamber may beconfigured so that, when the air flow rate inhaled by the user throughthe apparatus is 1.3 L min⁻¹, the average magnitude of velocity of airin the vaporizer element region is in the range 0-1.2 ms⁻¹. The averagemagnitude of velocity of air in the vaporizer element region may becalculated using computational fluid dynamics.

When the air flow rate inhaled by the user through the apparatus is 1.3L min⁻¹, the average magnitude of velocity of air in the vaporizerelement region may be not more than 0.001 ms⁻¹, or not more than 0.005ms⁻¹, or not more than 0.01 ms⁻¹, or not more than 0.05 ms⁻¹.

When the average magnitude of velocity of air in the vaporizer elementregion is in the ranges specified, it is considered that the resultantaerosol particle size is advantageously controlled to be in a desirablerange. It is further considered that the velocity of air in thevaporizer element region is more relevant to the resultant particle sizecharacteristics than consideration of the velocity in the vaporizationchamber as a whole. This is in view of the significant effect of thevelocity of air in the vaporizer element region on the cooling of thevapor emitted from the vaporizer element surface.

Additionally, or alternatively is it relevant to consider the maximummagnitude of velocity of air in the vaporizer element region.

Therefore, the air inlet, flow passage, outlet and the vaporizationchamber may be configured so that, when the air flow rate inhaled by theuser through the apparatus is 1.3 L min⁻¹, the maximum magnitude ofvelocity of air in the vaporizer element region is in the range 0-2.0ms⁻¹.

When the air flow rate inhaled by the user through the apparatus is 1.3L min⁻¹, the maximum magnitude of velocity of air in the vaporizerelement region may be not more than 0.001 ms⁻¹, or not more than 0.005ms⁻¹, or not more than 0.01 ms⁻¹, or not more than 0.05 ms⁻¹.

It is considered that configuring the apparatus in a manner to permitsuch control of velocity of the airflow at the vaporizer permits thegeneration of aerosols with particularly advantageous particle sizecharacteristics, including Dv50 values.

Additionally, or alternatively is it relevant to consider the turbulenceintensity in the vaporizer chamber in view of the effect of turbulenceon the particle size of the generated aerosol. For example, the airinlet, flow passage, outlet and the vaporization chamber may beconfigured so that, when the air flow rate inhaled by the user throughthe apparatus is 1.3 L min⁻¹, the turbulence intensity in the vaporizerelement region is not more than 1%.

When the air flow rate inhaled by the user through the apparatus is 1.3L min⁻¹, the turbulence intensity in the vaporizer element region may benot more than 0.95%, not more than 0.9%, not more than 0.85%, not morethan 0.8%, not more than 0.75%, not more than 0.7%, not more than 0.65%or not more than 0.6%.

It is considered that configuring the apparatus in a manner to permitsuch control of the turbulence intensity in the vaporizer element regionpermits the generation of aerosols with particularly advantageousparticle size characteristics, including Dv50 values.

Following detailed investigations, the inventors consider, withoutwishing to be bound by theory, that the particle size characteristics ofthe generated aerosol may be determined by the cooling rate experiencedby the vapor after emission from the vaporizer element (e.g., wick). Inparticular, it appears that imposing a relatively slow cooling rate onthe vapor has the effect of generating aerosols with a relatively largeparticle size. The parameters discussed above (velocity and turbulenceintensity) are considered to be mechanisms for implementing a particularcooling dynamic to the vapor.

More generally, it is considered that the air inlet, flow passage,outlet and the vaporization chamber may be configured so that a desiredcooling rate is imposed on the vapor. The particular cooling rate to beused depends of course on the nature of the aerosol precursor and otherconditions. However, for a particular aerosol precursor it is possibleto define a set of testing conditions in order to define the coolingrate, and by extension this imposes limitations on the configuration ofthe apparatus to permit such cooling rates as are shown to result inadvantageous aerosols. Accordingly, the air inlet, flow passage, outletand the vaporization chamber may be configured so that the cooling rateof the vapor is such that the time taken to cool to 50° C. is not lessthan 16 ms, when tested according to the following protocol. The aerosolprecursor is an e-liquid consisting of 1.6% freebase nicotine and theremainder a 65:35 propylene glycol and vegetable glycerin mixture, thee-liquid having a boiling point of 209° C. Air is drawn into the airinlet at a temperature of 25° C. The vaporizer is operated to release avapor of total particulate mass 5 mg over a 3 second duration from thevaporizer element surface in an air flow rate between the air inlet andoutlet of 1.3 L min⁻¹.

Additionally, or alternatively, the air inlet, flow passage, outlet andthe vaporization chamber may be configured so that the cooling rate ofthe vapor is such that the time taken to cool to 50° C. is not less than16 ms, when tested according to the following protocol. The aerosolprecursor is an e-liquid consisting of 1.6% freebase nicotine and theremainder a 65:35 propylene glycol and vegetable glycerin mixture, thee-liquid having a boiling point of 209° C. Air is drawn into the airinlet at a temperature of 25° C. The vaporizer is operated to release avapor of total particulate mass 5 mg over a 3 second duration from thevaporizer element surface in an air flow rate between the air inlet andoutlet of 2.0 L min⁻¹.

Cooling of the vapor such that the time taken to cool to 50° C. is notless than 16 ms corresponds to an equivalent linear cooling rate of notmore than 10° C./ms.

The equivalent linear cooling rate of the vapor to 50° C. may be notmore than 9° C./ms, not more than 8° C./ms, not more than 7° C./ms, notmore than 6° C./ms or not more than 5° C./ms.

Cooling of the vapor such that the time taken to cool to 50° C. is notless than 32 ms corresponds to an equivalent linear cooling rate of notmore than 5° C./ms.

The testing protocol set out above considers the cooling of the vapor(and subsequent aerosol) to a temperature of 50° C. This is atemperature which can be considered to be suitable for an aerosol toexit the apparatus for inhalation by a user without causing significantdiscomfort. It is also possible to consider cooling of the vapor (andsubsequent aerosol) to a temperature of 75° C. Although this temperatureis possibly too high for comfortable inhalation, it is considered thatthe particle size characteristics of the aerosol are substantiallysettled by the time the aerosol cools to this temperature (and they maybe settled at still higher temperature).

Accordingly, the air inlet, flow passage, outlet and the vaporizationchamber may be configured so that the cooling rate of the vapor is suchthat the time taken to cool to 75° C. is not less than 4.5 ms, whentested according to the following protocol. The aerosol precursor is ane-liquid consisting of 1.6% freebase nicotine and the remainder a 65:35propylene glycol and vegetable glycerin mixture, the e-liquid having aboiling point of 209° C. Air is drawn into the air inlet at atemperature of 25° C. The vaporizer is operated to release a vapor oftotal particulate mass 5 mg over a 3 second duration from the vaporizerelement surface in an air flow rate between the air inlet and outlet of1.3 L min⁻¹.

Additionally, or alternatively, the air inlet, flow passage, outlet andthe vaporization chamber may be configured so that the cooling rate ofthe vapor is such that the time taken to cool to 75° C. is not less than4.5 ms, when tested according to the following protocol. The aerosolprecursor is an e-liquid consisting of 1.6% freebase nicotine and theremainder a 65:35 propylene glycol and vegetable glycerin mixture, thee-liquid having a boiling point of 209° C. Air is drawn into the airinlet at a temperature of 25° C. The vaporizer is operated to release avapor of total particulate mass 5 mg over a 3 second duration from thevaporizer element surface in an air flow rate between the air inlet andoutlet of 2.0 L min⁻¹.

Cooling of the vapor such that the time taken to cool to 75° C. is notless than 4.5 ms corresponds to an equivalent linear cooling rate of notmore than 30° C./ms.

The equivalent linear cooling rate of the vapor to 75° C. may be notmore than 29° C./ms, not more than 28° C./ms, not more than 27° C./ms,not more than 26° C./ms, not more than 25° C./ms, not more than 24°C./ms, not more than 23° C./ms, not more than 22° C./ms, not more than21° C./ms, not more than 20° C./ms, not more than 19° C./ms, not morethan 18° C./ms, not more than 17° C./ms, not more than 16° C./ms, notmore than 15° C./ms, not more than 14° C./ms, not more than 13° C./ms,not more than 12° C./ms, not more than 11° C./ms or not more than 10°C./ms.

Cooling of the vapor such that the time taken to cool to 75° C. is notless than 13 ms corresponds to an equivalent linear cooling rate of notmore than 10° C./ms.

It is considered that configuring the apparatus in a manner to permitsuch control of the cooling rate of the vapor permits the generation ofaerosols with particularly advantageous particle size characteristics,including Dv50 values.

The disclosure includes the combination of the aspects and preferredfeatures described except where such a combination is clearlyimpermissible or expressly avoided.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the disclosure may be understood, and so that further aspectsand features thereof may be appreciated, embodiments illustrating theprinciples of the disclosure will now be discussed in further detailwith reference to the accompanying figures, in which:

FIG. 1 illustrates a set of rectangular tubes for use in experiments toassess the effect of flow and cooling conditions at the wick on aerosolproperties. Each tube has the same depth and length but different width.

FIG. 2 shows a schematic perspective longitudinal cross sectional viewof an example rectangular tube with a wick and heater coil installed.

FIG. 3 shows a schematic transverse cross sectional view an examplerectangular tube with a wick and heater coil installed. In this example,the internal width of the tube is 12 mm.

FIGS. 4A-4D show air flow streamlines in the four devices used in aturbulence study.

FIG. 5 shows the experimental set up to investigate the influence ofinflow air temperature on aerosol particle size, in order to investigatethe effect of vapor cooling rate on aerosol generation.

FIG. 6 shows a schematic longitudinal cross sectional view of a firstsmoking substitute apparatus (pod 1) used to assess influence of inflowair temperature on aerosol particle size.

FIG. 7 shows a schematic longitudinal cross sectional view of a secondsmoking substitute apparatus (pod 2) used to assess influence of inflowair temperature on aerosol particle size.

FIG. 8A shows a schematic longitudinal cross sectional view of a thirdsmoking substitute apparatus (pod 3) used to assess influence of inflowair temperature on aerosol particle size.

FIG. 8B shows a schematic longitudinal cross sectional view of the samethird smoking substitute apparatus (pod 3) in a direction orthogonal tothe view taken in FIG. 8A.

FIG. 9 shows a plot of aerosol particle size (Dv50) experimental resultsagainst calculated air velocity.

FIG. 10 shows a plot of aerosol particle size (Dv50) experimentalresults against the flow rate through the apparatus for a calculated airvelocity of 1 m/s.

FIG. 11 shows a plot of aerosol particle size (Dv50) experimentalresults against the average magnitude of the velocity in the vaporizersurface region, as obtained from CFD modelling.

FIG. 12 shows a plot of aerosol particle size (Dv50) experimentalresults against the maximum magnitude of the velocity in the vaporizersurface region, as obtained from CFD modelling.

FIG. 13 shows a plot of aerosol particle size (Dv50) experimentalresults against the turbulence intensity.

FIG. 14 shows a plot of aerosol particle size (Dv50) experimentalresults dependent on the temperature of the air and the heating state ofthe apparatus.

FIG. 15 shows a plot of aerosol particle size (Dv50) experimentalresults against vapor cooling rate to 50° C.

FIG. 16 shows a plot of aerosol particle size (Dv50) experimentalresults against vapor cooling rate to 75° C.

FIG. 17 is a schematic front view of a smoking substitute system,according to a first reference arrangement, in an engaged position;

FIG. 18 is a schematic front view of the smoking substitute system ofthe first reference arrangement in a disengaged position;

FIG. 19 is a schematic longitudinal cross sectional view of a smokingsubstitute apparatus of the first reference arrangement;

FIG. 20 is an enlarged schematic cross sectional view of part of the airpassage and aerosol generation chamber of the first referencearrangement;

FIG. 21A is an enlarged schematic cross sectional view of a smokingsubstitute system of a first embodiment, oriented upright in adisengaged position;

FIG. 21B is an enlarged schematic cross sectional view of the smokingsubstitute system of the first embodiment, oriented upright in anengaged position;

FIG. 22A is an enlarged schematic cross sectional view of a smokingsubstitute system of a second embodiment, oriented upright in adisengaged position; and

FIG. 22B is an enlarged schematic cross sectional view of the smokingsubstitute system of the second embodiment, oriented upright in anengaged position.

DETAILED DESCRIPTION

Further background to the present disclosure and further aspects andembodiments of the present disclosure will now be discussed withreference to the accompanying figures. Further aspects and embodimentswill be apparent to those skilled in the art. The contents of alldocuments mentioned in this text are incorporated herein by reference intheir entirety.

FIGS. 17 and 18 illustrate a smoking substitute system in the form of ane-cigarette system 110. The system 110 comprises a main body 120 of thesystem 110, and a smoking substitute apparatus in the form of ane-cigarette consumable (or “pod”) 150. In the illustrated embodiment theconsumable 150 (sometimes referred to herein as a smoking substituteapparatus) is removable from the main body 120, so as to be areplaceable component of the system 110. The e-cigarette system 110 is aclosed system in the sense that it is not intended that the consumableshould be refillable with e-liquid by a user.

As is apparent from FIGS. 17 and 18, the consumable 150 is configured toengage the main body 120. FIG. 17 shows the main body 120 and theconsumable 150 in an engaged state, whilst FIG. 18 shows the main body120 and the consumable 150 in a disengaged state. When engaged, aportion of the consumable 150 is received in a cavity of correspondingshape in the main body 120 and is retained in the engaged position byway of a snap-engagement mechanism. In other embodiments, the main body120 and consumable 150 may be engaged by screwing one into (or onto) theother, or through a bayonet fitting, or by way of an interference fit.

The system 110 is configured to vaporize an aerosol precursor, which inthe illustrated embodiment is in the form of a nicotine-based e-liquid160. The e-liquid 160 comprises nicotine and a base liquid includingpropylene glycol and/or vegetable glycerin. In the present embodiment,the e-liquid 160 is flavored by a flavorant. In other embodiments, thee-liquid 160 may be flavorless and thus may not include any addedflavorant.

FIG. 19 shows a schematic longitudinal cross sectional view of a smokingsubstitute apparatus according to a reference arrangement that isconfigured to form part of the smoking substitute system shown in FIGS.17 and 18. The smoking substitute apparatus, or consumable 150 as shownin FIG. 19 is provided as a reference arrangement to illustrate thefeatures of a consumable 150 and its interaction with the main body 120.In FIG. 19, the e-liquid 160 is stored within a reservoir in the form ofa tank 152 that forms part of the consumable 150. In the illustratedembodiment, the consumable 150 is a “single-use” consumable 150. Thatis, upon exhausting the e-liquid 160 in the tank 152, the intention isthat the user disposes of the entire consumable 150. The term“single-use” does not necessarily mean the consumable is designed to bedisposed of after a single smoking session. Rather, it defines theconsumable 150 is not arranged to be refilled after the e-liquidcontained in the tank 152 is depleted. The tank may include a vent (notshown) to allow ingress of air to replace e-liquid that has been usedfrom the tank. The consumable 150 preferably includes a window 158 (seeFIGS. 17 and 18), so that the amount of e-liquid in the tank 152 can bevisually assessed. The main body 120 includes a slot 157 so that thewindow 158 of the consumable 150 can be seen whilst the rest of the tank152 is obscured from view when the consumable 150 is received in thecavity of the main body 120. The consumable 150 may be referred to as a“clearomizer” when it includes a window 158, or a “cartomizer” when itdoes not.

In other embodiments, the e-liquid (i.e., aerosol precursor) may be theonly part of the system that is truly “single-use”. That is, the tankmay be refillable with e-liquid or the e-liquid may be stored in anon-consumable component of the system. For example, in such otherembodiments, the e-liquid may be stored in a tank located in the mainbody or stored in another component that is itself not single-use (e.g.,a refillable cartomizer).

The external wall of tank 152 is provided by a casing of the consumable150. The tank 152 annularly surrounds, and thus defines a portion of, apassage 170 that extends between a vaporizer inlet 172 and an outlet 174at opposing ends of the consumable 150. In this respect, the passage 170comprises an upstream end at the end of the consumable 150 that engageswith the main body 120, and a downstream end at an opposing end of theconsumable 150 that comprises a mouthpiece 154 of the system 110.

When the consumable 150 is received in the cavity of the main body 120as shown in FIG. 19, a plurality of device air inlets 176 are formed atthe boundary between the casing of the consumable and the casing of themain body. The device air inlets 176 are in fluid communication with thevaporizer inlet 172 through an inlet flow channel 178 formed in thecavity of the main body which is of corresponding shape to receive apart of the consumable 150. Air from outside of the system 110 cantherefore be drawn into the passage 170 through the device air inlets176 and the inlet flow channels 178.

When the consumable 150 is engaged with the main body 120, a user caninhale (i.e., take a puff) via the mouthpiece 154 so as to draw airthrough the passage 170, and so as to form an air flow (indicated by thedashed arrows in FIG. 19) in a direction from the vaporizer inlet 172 tothe outlet 174. Although not illustrated, the passage 170 may bepartially defined by a tube (e.g., a metal tube) extending through theconsumable 150. In FIG. 19, for simplicity, the passage 170 is shownwith a substantially circular cross-sectional profile with a constantdiameter along its length. In other arrangements and in someembodiments, the passage may have other cross-sectional profiles, suchas oval shaped or polygonal shaped profiles. Further, in otherarrangements and some embodiments, the cross sectional profile and thediameter (or hydraulic diameter) of the passage may vary along itslongitudinal axis.

The smoking substitute system 110 is configured to vaporize the e-liquid160 for inhalation by a user. To provide this operability, theconsumable 150 comprises an aerosol generator for example a heater, theheater having a porous wick 162 and a resistive heating element in theform of a heating filament 164 that is helically wound (in the form of acoil) around a portion of the porous wick 162. The porous wick 162extends across the passage 170 (i.e., transverse to a longitudinal axisof the passage 170 and thus also transverse to the air flow along thepassage 170 during use) and opposing ends of the wick 162 extend intothe tank 152 (so as to be immersed in the e-liquid 160). In this way,e-liquid 160 contained in the tank 152 is conveyed from the opposingends of the porous wick 162 to a central portion of the porous wick 162so as to be exposed to the air flow in the passage 170.

The helical filament 164 is wound about the exposed central portion ofthe porous wick 162 and is electrically connected to an electricalinterface in the form of electrical contacts 156 mounted at the end ofthe consumable that is proximate the main body 120 (when the consumableand the main body are engaged). When the consumable 150 is engaged withthe main body 120, electrical contacts 156 make contact withcorresponding electrical contacts (not shown) of the main body 120. Themain body electrical contacts are electrically connectable to a powersource (not shown) of the main body 120, such that (in the engagedposition) the filament 164 is electrically connectable to the powersource. In this way, power can be supplied by the main body 120 to thefilament 164 in order to heat the filament 164. This heats the porouswick 162 which causes e-liquid 160 conveyed by the porous wick 162 tovaporize and thus to be released from the porous wick 162. The vaporizede-liquid becomes entrained in the air flow and, as it cools in the airflow (between the heated wick and the outlet 174 of the passage 170),condenses to form an aerosol. This aerosol is then inhaled, via themouthpiece 154, by a user of the system 110. As e-liquid is lost fromthe heated portion of the wick, further e-liquid is drawn along the wickfrom the tank to replace the e-liquid lost from the heated portion ofthe wick.

The filament 164 and the exposed central portion of the porous wick 162are positioned across the passage 170. More specifically, the part ofpassage that contains the filament 164 and the exposed portion of theporous wick 162 forms a vaporization chamber, or aerosol generationchamber. In the illustrated example, the aerosol generation chamber hasthe same cross-sectional diameter as the passage 170. However, in otherembodiments the aerosol generation chamber may have a different crosssectional profile as the passage 170. For example, the aerosolgeneration chamber may have a larger cross sectional diameter than atleast some of the downstream part of the passage 170 so as to enable alonger residence time for the air inside the aerosol generation chamber.

FIG. 20 illustrates in more detail the aerosol generation chamber of thereference arrangement as shown in FIG. 3 and therefore the region of theconsumable 150 around the wick 162 and filament 164. The helicalfilament 164 is wound around a central portion of the porous wick 162.The porous wick extends across passage 170. E-liquid 160 containedwithin the tank 152 is conveyed as illustrated schematically by arrows401, i.e., from the tank and towards the central portion of the porouswick 162.

When the user inhales, air is drawn from through the inlets 176 shown inFIG. 19, along inlet flow channel 178 to aerosol generation chamberinlet 172 and into the aerosol generation chamber containing porous wick162. The porous wick 162 extends substantially transverse to the airflow direction. The air flow passes around the porous wick, at least aportion of the air flow substantially following the surface of theporous wick 162. In examples where the porous wick has a cylindricalcross-sectional profile, the air flow may follow a curved path around anouter periphery of the porous wick 162.

At substantially the same time as the air flow passes around the porouswick 162, the filament 164 is heated so as to vaporize the e-liquidwhich has been wicked into the porous wick. The air flow passing aroundthe porous wick 162 picks up this vaporized e-liquid, and thevapor-containing air flow is drawn in direction 403 further down passage170.

The power source of the main body 120 may be in the form of a battery(e.g., a rechargeable battery such as a lithium-ion battery). The mainbody 120 may comprise a connector in the form of e.g., a USB port forrecharging this battery. The main body 120 may also comprise acontroller that controls the supply of power from the power source tothe main body electrical contacts (and thus to the filament 164). Thatis, the controller may be configured to control a voltage applied acrossthe main body electrical contacts, and thus the voltage applied acrossthe filament 164. In this way, the filament 164 may only be heated undercertain conditions (e.g., during a puff and/or only when the system isin an active state). In this respect, the main body 120 may include apuff sensor (not shown) that is configured to detect a puff (i.e.,inhalation). The puff sensor may be operatively connected to thecontroller so as to be able to provide a signal, to the controller,which is indicative of a puff state (i.e., puffing or not puffing). Thepuff sensor may, for example, be in the form of a pressure sensor or anacoustic sensor.

Although not shown, the main body 120 and consumable 150 may comprise afurther interface which may, for example, be in the form of an RFIDreader, a barcode or QR code reader. This interface may be able toidentify a characteristic (e.g., a type) of a consumable 150 engagedwith the main body 120. In this respect, the consumable 150 may includeany one or more of an RFID chip, a barcode or QR code, or memory withinwhich is an identifier and which can be interrogated via the interface.

FIGS. 21A and 21B respectively illustrates an enlarged longitudinalcross sectional view of a smoking substitute system in a disengaged andan engaged position according to the first embodiment of the presentdisclosure. More specifically, the consumable 250 is configured toengage and disengage with the main body 120 and is interchangeable withthe reference arrangement 150 as shown in FIGS. 19 and 20. Furthermore,the consumable 250 is configured to interact with the main body 120 inthe same manner as the reference arrangement 150 and the user mayoperate the consumable 250 in the same manner as the referencearrangement 150. The consumable 250 in FIGS. 21A and 21B is shownoriented upright, which is an orientation the apparatus is put into whena user draws on the consumable 250.

The consumable 250 comprises a housing which defines an aerosolgeneration chamber 280 at a first end of the housing. The aerosolgeneration chamber 280 and housing shares the same longitudinal axisalong a dashed line as shown in FIG. 21A. Said first end of theconsumable 250 is configured to be received in a cavity of the main body120. The aerosol generation chamber 280 comprises a heater locatedadjacent to or above a base 284 of aerosol generation chamber 280. Theheater comprises a porous wick 262 and a heating filament 264 helicallywound around a portion of the porous wick 162. The end portions of theporous wick 262 is configured to be in fluid communication with a tank(not shown) and thereby allow aerosol precursor stored in the tank to bewicked towards the porous wick 262. In use, the heating element isenergized and thereby vaporizes aerosol precursor in the porous wick 262to form a vapor. A portion of the vapor may promptly cool in thevicinity of the heater and thereby condenses to form an aerosol. Theflow path of the aerosol and/or aerosol 414 is shown as dotted arrows inFIG. 21B.

As shown in FIGS. 21A and 21B, the aerosol generation chamber 280 takesthe form of an open ended container, or a cup, having a plurality ofchamber inlets 272 opened through the sidewall of the aerosol generationchamber 280 and opposite to each other. In some embodiments, a singlechamber inlet may be provided. In other embodiments, the plurality ofchamber inlets are arranged circumferentially on the sidewall aerosolgeneration chamber 280. In the illustrated embodiment, the aerosolgeneration chamber 280 is defined by the housing, e.g., the aerosolgeneration chamber 280 and housing share the same sidewall. Therefore,the chamber inlets 272 also form the air inlets of the housing.

The aerosol generation chamber 280 further comprises a chamber outlet282 opened towards an outlet (not shown) at the second end of thehousing opposite the first end. The second end of the consumable 250comprises a mouthpiece 254 onto which a user may puff, in order to drawan air flow through the chamber inlets 272 and aerosol generationchamber 280 before exhausting through the chamber outlet 282 and theoutlet. Substantially all of the air flow entering the chamber inlet isdirected away from the heater. The flow path of the air flow 412 isshown as solid arrows in FIG. 21B.

As clearly illustrated in FIG. 21B, in the upright orientation, thechamber inlets 272 are positioned higher than the heater and thereforethe aerosol generation chamber 280 is sealed against air flow into andout of the chamber 280 at least in a region level with or below theposition of the heater. That is, the chamber inlets 272 are shownpositioned between the heater and the chamber outlet 282 along thelongitudinal axis of the aerosol generation chamber. More specifically,the chamber inlets 272 are provided downstream of heater in thedirection of aerosol flow, e.g., the direction where generated aerosolflows from the heater towards the chamber outlet 282. Furthermore, thechamber inlets 272 and chamber outlet 282 form the only apertures at theaerosol generation chamber 280 that allow gas flow passage.

In some other embodiments, the base of aerosol generation chamber maypermit only an insignificant amount of air to ingress into the aerosolgeneration chamber, e.g., through a gap or an aperture formed at saidbase.

As aerosol precursor is vaporized from the heated portion of the wick,further aerosol precursor is drawn along the wick from the tank toreplace said vaporized aerosol precursor. In some cases, excess aerosolprecursor may be drawn, by momentum or by gravity, into the wick andsubsequently collected in the aerosol generation chamber 280, e.g., atthe base of the aerosol generation chamber 280. Such arrangement mayreduce or eliminate excess aerosol precursor in the porous wick 262leaking through the consumable 250, e.g., said excess aerosol precursoris retained and subsequently collected at the base of aerosol generationchamber by gravity.

In contrast with the consumable 150 as shown in FIGS. 19 and 20 wherethe air flow passes over the heater, the flow path 412 of substantiallyall of the air flow entering the aerosol generation chamber 280 of thepresent embodiment is directed away and spaced from the heater. Becauseas the air flow enters through the chamber inlets 272 at the sidewall,it enters the aerosol generation chamber 280 in a direction away fromthe aerosol generator, e.g., in a radial direction and parallel to theheater, the resulting air flow path 412 does not directly impinge uponthe heater. Such arrangement reduces the turbulence in the vicinity ofthe heater and thereby allows aerosol precursor to be vaporized inabsence of a direct air flow. Therefore, the vicinity of the heater maybe considered to be a “stagnant” volume. For example, volumetricflowrate of vapor and/or aerosol in the vicinity of the heater may beless than 0.1 liter per minute. The vaporized aerosol precursor, orvapor, may cool and therefore condense in the vicinity of the heater toform an aerosol, which is subsequently merged or entrained with the airflow passing along flow path 412. In addition, a portion of thevaporized aerosol precursor may not immediately condense in the vicinityof the heater but may cool to form an aerosol as it entrains into theair flow passing along flow path 412. With the absence of, or muchreduced, air flow in the vicinity of the heater, the aerosol asgenerated by the illustrated embodiment has a droplet size d₅₀ of atleast 1 μm. More preferably, the aerosol as generated by the illustratedembodiment has a droplet size d₅₀ of ranged between 2 μm to 3 μm.

In the illustrated embodiment, the aerosol generation chamber isconfigured to have a length of 20 mm and a volume of 680 mm³. In otherembodiments the aerosol generation chamber may be configured to have aninternal volume ranging between 68 mm³ to 680 mm³, wherein the length ofthe aerosol generation chamber may range between 2 mm to 20 mm.

In the illustrated embodiment, the heater is positioned at the base 284of the aerosol generation chamber 280, e.g., the heater is spaced fromthe chamber inlets 272. Such arrangement may reduce the amount of airflow that may interact with the heater, and therefore it may minimizethe amount of turbulence in the vicinity of the heater. Furthermore,such arrangement may increase the residence time of vapor in thestagnant aerosol generation chamber 280 for the vapor to cool andcondense, and thereby it may result in the formation of larger aerosoldroplets. Additionally, such arrangement may allow excess aerosolprecursor collected at the base of the aerosol generation chamber to beabsorbed into the wick, and thereby reduces the likelihood of leakage ofsaid excess aerosol precursor.

In some other embodiments, the heater may be positioned adjacent to, orimmediately upstream of, the chamber inlets along the longitudinal axisof the housing, and therefore that the flow path of aerosol from theheater to merge with the air flow may be shortened. This may allowaerosol to entrain with the air flow in a more efficient manner.

When the consumable 250 is put in an upright orientation, a region ofthe aerosol generation chamber 280 level with and below the aerosolgenerator is sealed against air flow into and out of the chamber 280.This differs to the reference arrangement as shown in FIGS. 17 and 18which comprises an air inlet formed at the base of the aerosolgeneration chamber. The heating filament 284 is electrically connectedto electrical contacts 256 through sealed apertures at the base 284 ofthe aerosol generation chamber 280. Such arrangement prevents airingress, as well as fluid leakage, through the base 284 of the aerosolgeneration chamber 280. As shown in FIG. 21B, when the first end of theconsumable 250 is received into the main body 120, the electricalcontacts 256 contact corresponding electrical contacts 259 in the cavityof the main body 120. As such, the heater is put in electricalconnection with the power source in the main body 120.

In FIGS. 21A and 21B the electrical contacts 256 have an electricallyconductive surface provided at the external surface of base 284 andextends orthogonally to the longitudinal axis of the housing. Similarly,the corresponding electrical contacts 259 have an electricallyconductive surface provided at the internal surface of cavity of themain body and extends orthogonally to the longitudinal axis of the mainbody. As shown in FIG. 21B, the electrical contacts 256 overlay thecorresponding electrical contacts 259 in the engaged position. One, orboth, of the electrical contacts 259 and the corresponding electricalcontacts 259 may be resiliently movable in the axial direction. Forexample, the electrical contacts 256 and corresponding electricalcontacts 259 may comprise a cantilever spring or coil spring. Theresilient movement may help to ensure a secure electrical connection.The electrical contacts 256 may have the same configuration ascorresponding electrical contacts 259.

FIGS. 22A and 22B respectively illustrates an enlarged longitudinalcross sectional view of a smoking substitute system in a disengaged andan engaged position according to a second embodiment of the presentdisclosure. The system comprises a main body 320, and a consumable 350configured to slide into a cavity of the main body 320 to form anengagement between the two. More specifically, the consumable 350 andmain body 320 in this illustrated embodiment is structurally similar tothe consumable 250 and main body 120 shown in FIGS. 21A and 21B, andoperates in the same manner to generate an aerosol. The consumable 350and main body 320 in this illustrated embodiment however, compriseselectrical contacts 356 that are formed on the external sidewall of theconsumable 350 for establishing electrical connection with correspondingelectrical contacts 359 formed on the internal sidewall of the cavity ofthe main body 320.

The electrical contacts 356 have an electrically conductive surfacewhich is parallel to the longitudinal axis of the housing. Thecorresponding electrical contacts 359 have an electrically conductivesurface which is parallel to the longitudinal axis of the main body 320.The electrical contacts 356 and corresponding electrical contacts 359lie against one another in the engaged position. The electrical contacts356 and corresponding electrical contacts 359 may physically slideagainst one another as the consumable 350 is moved into the engagedposition. One, or both, of the electrical contacts 356 and correspondingelectrical contacts 359 may be resiliently movable in the radialdirection. For example, the electrical contacts 356 and correspondingelectrical contacts 359 may comprise a cantilever spring or coil spring.The resilient movement may help to ensure a secure electricalconnection. The electrical contacts 356 may have the same configurationas corresponding electrical contacts 359.

As illustrated in FIGS. 22A and 22B, a pair of electrically conductivesurfaces are provided in each of the electrical contacts 356 andcorresponding electrical contacts 359. The pairing of electricallyconductive surfaces is shown at diametrically opposite locations on theconsumable 350 and the cavity of the main body 320. This providesmaximum physical separation of pair of electrically conductive surface.In other embodiments the electrical contacts 356 and correspondingelectrical contacts 359 may be respectively located at other positionsaround the perimeter of the housing of the consumable 150 and around theperimeter of the cavity of the main body 120.

In other embodiments, the electrical contacts are provided on anexternal surface at the side of consumable housing and correspondingelectrical contacts are provided on an internal surface at the side ofthe cavity of the main body. The electrical contacts and correspondingelectrical contacts may overlay and press against one another in anaxial direction (i.e., parallel to the longitudinal axis of the housingor of the main body) in the engaged position. One, or both, of theelectrical connects and corresponding electrical contacts may beresiliently movable in the axial direction. For example, as theconsumable is moved into the engaged position, corresponding contacts inthe cavity are movable axially inwardly, while continuing to exert aforce against electrical contacts of the consumable. The resilientmovement may help to ensure a secure electrical connection. Theelectrical contacts may have the same configuration as correspondingelectrical contacts.

EXAMPLES

There now follows a disclosure of certain examples of experimental workundertaken to determine the effects of certain conditions in the smokingsubstitute apparatus on the particle size of the generated aerosol.However, the present disclosure is to be understood to not be limited inits application to the specific experimentation, results, and laboratoryprocedures disclosed herein after. Rather, the Examples are simplyprovided as one of various embodiments and are meant to be exemplary,not exhaustive.

The experimental work described in this example is relevant to theembodiments disclosed above in view of the “stagnant chamber” nature ofthe embodiments. The experimental work described in this example showsthat control over the flow conditions at the wick has an effect on theparticle size of the generated aerosol.

Introduction

Aerosol droplet size is a considered to be an important characteristicfor smoking substitution devices. Droplets in the range of 2-5 μm arepreferred in order to achieve improved nicotine delivery efficiency andto minimize the hazard of second-hand smoking. However, at the time ofwriting (September 2019), commercial EVP devices typically deliveraerosols with droplet size averaged around 0.5 μm, and to the knowledgeof the inventors not a single commercially available device can deliveran aerosol with an average particle size exceeding 1 μm.

The present inventors speculate, without themselves wishing to be boundby theory, that there has to date been a lack of understanding in themechanisms of e-liquid evaporation, nucleation and droplet growth in thecontext of aerosol generation in smoking substitute devices. The presentinventors have therefore studied these issues in order to provideinsight into mechanisms for the generation of aerosols with largerparticles. The present inventors have carried out experimental andmodelling work described in this example alongside theoreticalinvestigations, leading to significant achievements as now reported.

This disclosure considers the roles of air velocity, air turbulence andvapor cooling rate in affecting aerosol particle size.

Examples

In this work, a Malvern PANalytical Spraytec laser diffraction systemwas employed for the particle size measurement. In order to limit thenumber of variables, the same coil and wick (1.5 ohms Ni—Cr coil, 1.8 mmY07 cotton wick), the same e-liquid (1.6% freebase nicotine, 65:35propylene glycol (PG)/vegetable glycerin (VG) ratio, no added flavor)and the same input power (10 W) were used in all experiments describedin this example. Y07 represents the grade of cotton wick, meaning thatthe cotton has a linear density of 0.7 grams per meter.

Particle sizes were measured in accordance with ISO 13320:2009(E), whichis an international standard on laser diffraction methods for particlesize analysis. This is particularly well suited to aerosols, becausethere is an assumption in this standard that the particles are spherical(which is a good assumption for liquid-based aerosols). The standard isstated to be suitable for particle sizes in the range 0.1 micron to 3mm.

The results presented here concentrate on the volume-based medianparticle size Dv50. This is to be taken to be the same as the parameterd₅₀ used above.

Rectangular Tube Testing

The work reported here based on the inventors' insight that aerosolparticle size might be related to: 1) air velocity; 2) flow rate; and 3)Reynolds number. In a given EVP device, these three parameters areinter-linked to each other, making it difficult to draw conclusions onthe roles of each individual factor. In order to decouple these factors,experiments in this example were carried out using a set of rectangulartubes having different dimensions. These were manufactured by 3Dprinting. The rectangular tubes were 3D printed in an MJP 2500 3Dprinter. FIG. 1 illustrates the set of rectangular tubes. Each tube hasthe same depth and length but different width. Each tube has an integralend plate in order to provide a seal against air flow outside the tube.Each tube also has holes formed in opposing side walls in order toaccommodate a wick.

FIG. 2 shows a schematic perspective longitudinal cross sectional viewof an example rectangular tube 1170 with a wick 1162 and heater coil1164 installed. The location of the wick is about half way along thelength of the tube. This is intended to allow the flow of air along thetube to settle before reaching the wick.

FIG. 3 shows a schematic transverse cross sectional view an examplerectangular tube 1170 with a wick 1162 and heater coil 1164 installed.In this example, the internal width of the tube is 12 mm.

The rectangular tubes were manufactured to have same internal depth of 6mm in order to accommodate the standardized coil and wick, however thetube internal width varied from 4.5 mm to 50 mm. In this disclosure, the“tube size” is referred to as the internal width of rectangular tubes.

The rectangular tubes with different dimensions were used to generateaerosols that were tested for particle size in a Malvern PANalyticalSpraytec laser diffraction system. An external digital power supply wasdialed to 2.6 A constant current to supply 10 W power to the heater coilin all experiments described in this example. Between two runs, the wickwas saturated manually by applying one drop of e-liquid on each side ofthe wick.

Three groups of experiments were carried out in this example:

1.3 lpm (liters per minute, L min⁻¹ or LPM) constant flow rate ondifferent size tubes 2.0 lpm constant flow rate on different size tubes1 m/s constant air velocity on 3 tubes: i) 5 mm tube at 1.4 lpm flowrate; ii) 8 mm tube at 2.8 lpm flow rate; and iii) 20 mm tube at 8.6 lpmflow rate.

Table 1 shows a list of experiments in this example. The values in the“calculated air velocity” column were obtained by simply dividing theflow rate by the intersection area at the center plane of wick. Reynoldsnumbers (Re) were calculated through the following equation:

${Re} = \frac{\rho{vL}}{\mu}$

where: ρ is the density of air (1.225 kg/m³); ν is the calculated airvelocity in table 1; μ is the viscosity of air (1.48×10⁻⁵ m²/s); L isthe characteristic length calculated by:

$L = \frac{4P}{A}$

where: P is the perimeter of the flow path's intersection, and A is thearea of the flow path's intersection.

TABLE 1 List of experiments described in the rectangular tube exampleCalculated air Tube size Flow rate Reynolds velocity [mm] [lpm] number[m/s] 1.3 lpm 4.5 1.3 153 1.17 constant 6 1.3 142 0.71 flow rate 7 1.3136 0.56 8 1.3 130 0.47 10 1.3 120 0.35 12 1.3 111 0.28 20 1.3 86 0.1550 1.3 47 0.06 4.5 2.0 236 1.81 2.0 lpm 5 2.0 230 1.48 constant 6 2.0219 1.09 flow rate 8 2.0 200 0.72 12 2.0 171 0.42 20 2.0 132 0.23 50 2.072 0.09 1.0 m/s 5.0 1.4 155 1.00 constant air 8 2.8 279 1.00 velocity 208.6 566 1.00

Five repetition runs were carried out for each tube size and flow ratecombination. Between adjacent runs there were at least 5 minutes waittime for the Spraytec system to be purged. In each run, real timeparticle size distributions were measured in the Spraytec laserdiffraction system at a sampling rate of 2500 per second, the volumedistribution median (Dv50) was averaged over a puff duration of 4seconds. Measurement results were averaged and the standard deviationswere calculated to indicate errors as shown in section 4 below.

Turbulence Tube Testing

The Reynolds numbers in Table 1 are all well below 1000, therefore, itis considered fair to assume all the experiments described in thisexample would be under conditions of laminar flow. Further experimentswere carried out in this example and reported in this section toinvestigate the role of turbulence.

Turbulence intensity was introduced as a quantitative parameter toassess the level of turbulence. The definition and simulation ofturbulence intensity is discussed below.

Different device designs were considered in order to introduceturbulence. In the experiments described in this example, jetting panelswere added in the existing 12 mm rectangular tubes upstream of the wick.This approach enables direct comparison between different devices asthey all have highly similar geometry, with turbulence intensity beingthe only variable.

FIGS. 4A-4D show air flow streamlines in the four devices used in thisturbulence study. FIG. 4A is a standard 12 mm rectangular tube with wickand coil installed as explained in the previous section, with no jettingpanel. FIG. 4B has a jetting panel located 10 mm below (upstream from)the wick. FIG. 4C has the same jetting panel 5 mm below the wick. FIG.4D has the same jetting panel 2.5 mm below the wick. As can be seen fromFIGS. 4B-4D, the jetting panel has an arrangement of apertures shapedand directed in order to promote jetting from the downstream face of thepanel and therefore to promote turbulent flow. Accordingly, the jettingpanel can introduce turbulence downstream, and the panel causes higherlevel of turbulence near the wick when it is positioned closer to thewick. As shown in FIGS. 4A-4D, the four geometries gave turbulenceintensities of 0.55%, 0.77%, 1.06% and 1.34%, respectively, with FIG. 4Abeing the least turbulent, and FIG. 4D being the most turbulent.

For each of FIGS. 4A-4D, there are shown three modelling images. Theimage on the left shows the original image (color in the original), thecentral image shows a greyscale version of the image and the right-handimage shows a black and white version of the image. As will beappreciated, each version of the image highlights slightly differentfeatures of the flow. Together, they give a reasonable picture of theflow conditions at the wick.

These four devices were operated to generate aerosols following theprocedure explained above using a flow rate of 1.3 lpm and the generatedaerosols were tested for particle size in the Spraytec laser diffractionsystem.

High Temperature Testing

The experiment described in this example aimed to investigate theinfluence of inflow air temperature on aerosol particle size, in orderto investigate the effect of vapor cooling rate on aerosol generation.

The experimental set up is shown in FIG. 5. The testing used a CarboliteGero EHA 12300B tube furnace 3210 with a quartz tube 3220 to heat up theair. Hot air in the tube furnace was then led into a transparent housing3158 that contains the EVP device 3150 to be tested. A thermocouplemeter 3410 was used to assess the temperature of the air pulled into theEVP device. Once the EVP device was activated, the aerosol was pulledinto the Spraytec laser diffraction system 3310 via a silicone connector3320 for particle size measurement.

Three smoking substitute apparatuses (referred to as “pods”) were testedin the study: pod 1 is the commercially available “myblu optimized” pod(FIG. 6); pod 2 is a pod featuring an extended inflow path upstream ofthe wick (FIG. 7); and pod 3 is pod with the wick located in a stagnantvaporization chamber and the inlet air bypassing the vaporizationchamber but entraining the vapor from an outlet of the vaporizationchamber (FIGS. 8A and 8B).

Pod 1, shown in longitudinal cross sectional view (in the width plane)in FIG. 6, has a main housing that defines a tank 160 x holding ane-liquid aerosol precursor. Mouthpiece 154 x is formed at the upper partof the pod. Electrical contacts 156 x are formed at the lower end of thepod. Wick 162 x is held in a vaporization chamber. The air flowdirection is shown using arrows.

Pod 2, shown in longitudinal cross sectional view (in the width plane)in FIG. 7, has a main housing that defines a tank 160 y holding ane-liquid aerosol precursor. Mouthpiece 154 y is formed at the upper partof the pod. Electrical contacts 156 y are formed at the lower end of thepod. Wick 162 y is held in a vaporization chamber. The air flowdirection is shown using arrows. Pod 2 has an extended inflow path(plenum chamber 157 y) with a flow conditioning element 159 y,configured to promote reduced turbulence at the wick 162 y.

FIG. 8A shows a schematic longitudinal cross sectional view of pod 3.FIG. 8B shows a schematic longitudinal cross sectional view of the samepod 3 in a direction orthogonal to the view taken in FIG. 8A. Pod 3 hasa main housing that defines a tank 160 z holding an e-liquid aerosolprecursor. Mouthpiece 154 z is formed at the upper part of the pod.Electrical contacts 156 z are formed at the lower end of the pod. Wick162 z is held in a vaporization chamber. The air flow direction is shownusing arrows. Pod 3 uses a stagnant vaporizer chamber, with the airinlets bypassing the wick and picking up the vapor/aerosol downstream ofthe wick.

All three pods were filled with the same e-liquid (1.6% freebasenicotine, 65:35 PG/VG ratio, no added flavor). Three experimentsdescribed in this example were carried out for each pod: 1) standardmeasurement in ambient temperature; 2) only the inlet air was heated to50° C.; and 3) both the inlet air and the pods were heated to 50° C.Five repetition runs were carried out for each experiment and the Dv50results were taken and averaged.

Modelling Work

In this study, modelling work was performed using COMSOL Multiphysics5.4, engaged physics include: 1) laminar single-phase flow; 2) turbulentsingle-phase flow; 3) laminar two-phase flow; 4) heat transfer influids; and (5) particle tracing. Data analysis and data visualizationwere mostly completed in MATLAB R2019a.

Velocity Modelling

Air velocity in the vicinity of the wick is believed to play animportant role in affecting particle size. In this example, the airvelocity was calculated by dividing the flow rate by the intersectionarea, which is referred to as “calculated velocity” in this work. Thisinvolves a very crude simplification that assumes velocity distributionto be homogeneous across the intersection area.

In order to increase reliability of the work, computational fluiddynamics (CFD) modelling was performed to obtain more accurate velocityvalues.

The average velocity in the vicinity of the wick (defined as a volumefrom the wick surface to 1 mm away from the wick surface).

The maximum velocity in the vicinity of the wick (defined as a volumefrom the wick surface to 1 mm away from the wick surface).

TABLE 2 Average and maximum velocity in the vicinity of wick surfaceobtained from CFD modelling Calculated Average Maximum Tube size Flowrate velocity* velocity** Velocity** [mm] [lpm] [m/s] [m/s] [m/s] 1.3lpm 4.5 1.3 1.17 0.99 1.80 constant 6 1.3 0.71 0.66 1.22 flow rate 7 1.30.56 0.54 1.01 8 1.3 0.47 0.46 0.86 10 1.3 0.35 0.35 0.66 12 1.3 0.280.27 0.54 20 1.3 0.15 0.15 0.32 50 1.3 0.06 0.05 0.12 2.0 lpm 4.5 2.01.81 1.52 2.73 constant 5 2.0 1.48 1.31 2.39 flow rate 6 2.0 1.09 1.021.87 8 2.0 0.72 0.71 1.31 12 2.0 0.42 0.44 0.83 20 2.0 0.23 0.24 0.49 502.0 0.09 0.08 0.19 Calculated by dividing flow rate with intersectionarea **Obtained from CFD modelling

The CFD model uses a laminar single-phase flow setup. For eachexperiment described in this example, the outlet was configured to acorresponding flowrate, the inlet was configured to bepressure-controlled, the wall conditions were set as “no slip”. A 1 mmwide ring-shaped domain (wick vicinity) was created around the wicksurface, and domain probes were implemented to assess the average andmaximum magnitudes of velocity in this ring-shaped wick vicinity domain.

The CFD model outputs the average velocity and maximum velocity in thevicinity of the wick for each set of experiments carried out in theabove example. The outcomes are reported in Table 2.

Turbulence Modelling

Turbulence intensity (l) is a quantitative value that represents thelevel of turbulence in a fluid flow system. It is defined as the ratiobetween the root-mean-square of velocity fluctuations, u′, and theReynolds-averaged mean flow velocity, U:

$I = {\frac{u^{\prime}}{U} = {\frac{\sqrt{\frac{1}{3}\left( {{u^{\prime}}_{x}^{2} + {u^{\prime}}_{y}^{2} + {u^{\prime}}_{z}^{2}} \right)}}{\sqrt{{\overset{\_}{u_{x}}}^{2} + {\overset{\_}{u_{y}}}^{2} + {\overset{\_}{u_{z}}}^{2}}} = \frac{\sqrt{\frac{1}{3}\left\lbrack {\left( {u_{x}\overset{\_}{u_{x}}} \right)^{2} + \left( {u_{y} - \overset{\_}{u_{y}}} \right)^{2} + {+ \left( {u_{Z} - \overset{\_}{u_{z}}} \right)^{2}}} \right\rbrack}}{\sqrt{{\overset{\_}{u_{x}}}^{2} + {\overset{\_}{u_{Y}}}^{2} + {\overset{\_}{u_{Z}}}^{2}}}}}$

where u_(x), u_(y) and u_(z) are the x-, y- and z-components of thevelocity vector, u_(x) , u_(y) , and u_(z) represent the averagevelocities along three directions.

Higher turbulence intensity values represent higher levels ofturbulence. As a rule of thumb, turbulence intensity below 1% representsa low-turbulence case, turbulence intensity between 1% and 5% representsa medium-turbulence case, and turbulence intensity above 5% represents ahigh-turbulence case.

In this study, turbulence intensity was obtained from CFD simulationusing turbulent single-phase setup in COMSOL Multiphysics. For each ofthe four experiments described in this example, the outlet was set to1.3 lpm, the inlet was set to be pressure-controlled, and all wallconditions were set to be “no slip”.

Turbulence intensity was assessed within the volume up to 1 mm away fromthe wick surface (defined as the wick vicinity domain). For the fourexperiments described in this example, the turbulence intensities are0.55%, 0.77%, 1.06% and 1.34%, respectively, as also shown in FIGS.4A-4D.

Cooling Rate Modelling

The cooling rate modelling involves three coupling models in COMSOLMultiphysics: 1) laminar two-phase flow; 2) heat transfer in fluids, and3) particle tracing. The model is setup in three steps:

Set Up Two Phase Flow Model

Laminar mixture flow physics was selected in this study. The outlet wasconfigured in the same way as in the example above. However, this modelincludes two fluid phases released from two separate inlets: the firstone is the vapor released from wick surface, at an initial velocity of2.84 cm/s (calculated based on 5 mg total particulate mass over 3seconds puff duration) with initial velocity direction normal to thewick surface; the second inlet is air influx from the base of tube, therate of which is pressure-controlled.

Set Up Two-Way Coupling with Heat Transfer Physics

The inflow and outflow settings in heat transfer physics was configuredin the same way as in the two-phase flow model. The air inflow was setto 25° C., and the vapor inflow was set to 209° C. (boiling temperatureof the e-liquid formulation). In the end, the heat transfer physics isconfigured to be two-way coupled with the laminar mixture flow physics.The above model reaches steady state after approximately 0.2 second witha step size of 0.001 second.

Set Up Particle Tracing

A wave of 2000 particles were release from wick surface at t=0.3 secondafter the two-phase flow and heat transfer model has stabilized. Theparticle tracing physics has one-way coupling with the previous model,which means the fluid flow exerts dragging force on the particles,whereas the particles do not exert counterforce on the fluid flow.Therefore, the particles function as moving probes to output vaportemperature at each timestep.

The model outputs average vapor temperature at each time steps. A MATLABscript was then created to find the time step when the vapor cools to atarget temperature (50° C. or 75° C.), based on which the vapor coolingrates were obtained (Table 3).

TABLE 3 Average vapor cooling rate obtained from Multiphysics modellingCooling rate to Cooling rate to Tube size Flow rate 50° C. 75° C. [mm][lpm] [° C./ms] [° C./ms] 1.3 lpm 4.5 1.3 11.4  44.7 constant 6 1.3 5.4814.9 flow rate 7 1.3 3.46 7.88 8 1.3 2.24 5.15 10 1.3 1.31 2.85 12 1.3 0.841 1.81 20 1.3 0*   0.536 50 1.3 0   0 2.0 lpm 4.5 2.0 19.9  670constant 5 2.0 13.3  67 flow rate 6 2.0 8.83 26.8 8 2.0 3.61 8.93 12 2.01.45 3.19 20 2.0  0.395 0.761 50 2.0 0   0 *Zero cooling rate when theaverage vapor temperature is still above target temperature after 0.5second

Results and Discussions

Particle size measurement results for the rectangular tube testing areshown in Table 4. For every tube size and flow rate combination, fiverepetition runs were carried out in the Spraytec laser diffractionsystem. The Dv50 values from five repetition runs were averaged, and thestandard deviations were calculated to indicate errors, as shown inTable 4.

In this example, the roles of different factors affecting aerosolparticle size will be discussed based on experimental and modellingresults described in this example.

TABLE 4 Particle size measurement results for the rectangular tubetesting Dv50 standard Tube size Flow rate Dv50 average deviation [mm][lpm] [μm] [μm] 1.3 lpm 4.5 1.3 0.971 0.125 constant 6 1.3 1.697 0.341flow rate 7 1.3 2.570 0.237 8 1.3 2.705 0.207 10 1.3 2.783 0.184 12 1.33.051 0.325 20 1.3 3.116 0.354 50 1.3 3.161 0.157 2.0 lpm 4.5 2.0 0.5680.039 constant 5 2.0 0.967 0.315 flow rate 6 2.0 1.541 0.272 8 2.0 1.6460.363 12 2.0 3.062 0.153 20 2.0 3.566 0.260 50 2.0 3.082 0.440 m/sconstant 5.0 1.4 1.302 0.187 air velocity 8 2.8 1.303 0.468 20 8.6 1.4630.413

Decouple the Factors Affecting Particle Size

The particle size (Dv50) experimental results described in this exampleare plotted against calculated air velocity in FIG. 9. The graph shows astrong correlation between particle size and air velocity.

Different size tubes were tested at two flow rates: 1.3 lpm and 2.0 lpm.Both groups of data show the same trend that slower air velocity leadsto larger particle size. The conclusion was made more convincing by thefact that these two groups of data overlap well in FIG. 9: for example,the 6 mm tube delivered an average Dv50 of 1.697 μm when tested at 1.3lpm flow rate, and the 8 mm tube delivered a highly similar average Dv50of 1.646 μm when tested at 2.0 lpm flow rate, as they have similar airvelocity of 0.71 and 0.72 m/s, respectively.

In addition, FIG. 10 shows the results of three experiments described inthis example with highly different setup arrangements: 1) 5 mm tubemeasured at 1.4 lpm flow rate with Reynolds number of 155; 2) 8 mm tubemeasured at 2.8 lpm flow rate with Reynolds number of 279; and 3) 20 mmtube measured at 8.6 lpm flow rate with Reynolds number of 566. It isrelevant that these setup arrangements have one similarity: the airvelocities are all calculated to be 1 m/s. FIG. 10 shows that, althoughthese three sets of experiments have different tube sizes, flow ratesand Reynolds numbers, they all delivered similar particle sizes, as theair velocity was kept constant. These three data points were alsoplotted out in FIG. 9 (1 m/s data with star marks) and they tie innicely into particle size-air velocity trendline.

The above results lead to a strong conclusion that air velocity is animportant factor affecting the particle size of EVP devices. Relativelylarge particles are generated when the air travels with slower velocityaround the wick. It can also be concluded that flow rate, tube size andReynolds number are not necessarily independently relevant to particlesize, providing the air velocity is controlled in the vicinity of thewick.

Further Consideration of Velocity

In FIG. 9 the “calculated velocity” was obtained by dividing the flowrate by the intersection area, which is a crude simplification thatassumes a uniform velocity field. In order to increase reliability ofthe work, CFD modelling has been performed to assess the average andmaximum velocities in the vicinity of the wick. In this study, the“vicinity” was defined as a volume from the wick surface up to 1 mm awayfrom the wick surface.

The particle size measurement data were plotted against the averagevelocity (FIG. 11) and maximum velocity (FIG. 12) in the vicinity of thewick, as obtained from CFD modelling.

The data in these two graphs indicates that in order to obtain anaerosol with Dv50 larger than 1 μm, the average velocity should be lessthan or equal to 1.2 m/s in the vicinity of the wick and the maximumvelocity should be less than or equal to 2.0 m/s in the vicinity of thewick.

Furthermore, in order to obtain an aerosol with Dv50 of 2 μm or larger,the average velocity should be less than or equal to 0.6 m/s in thevicinity of the wick and the maximum velocity should be less than orequal to 1.2 m/s in the vicinity of the wick.

It is considered that typical commercial EVP devices deliver aerosolswith Dv50 around 0.5 μm, and there is no commercially available devicethat can deliver aerosol with Dv50 exceeding 1 μm. It is considered thattypical commercial EVP devices have average velocity of 1.5-2.0 m/s inthe vicinity of the wick.

The Role of Turbulence

The role of turbulence has been investigated in terms of turbulenceintensity, which is a quantitative characteristic that indicates thelevel of turbulence. In this work, four tubes of different turbulenceintensities were used to general aerosols which were measured in theSpraytec laser diffraction system. The particle size (Dv50) experimentalresults described in this example are plotted against turbulenceintensity in FIG. 13.

The graph suggests a correlation between particle size and turbulenceintensity, that lower turbulence intensity is beneficial for obtaininglarger particle size. It is noted that when turbulence intensity isabove 1% (medium-turbulence case), there are relatively largemeasurement fluctuations. In FIG. 13, the tube with a jetting panel 10mm below the wick has the largest error bar, because air jets becomeunpredictable near the wick after traveling through a long distance.

The results clearly indicate that laminar air flow is favorable for thegeneration of aerosols with larger particles, and that the generation oflarge particle sizes is jeopardized by introducing turbulence. In FIG.13, the 12 mm standard rectangular tube (without jetting panel) deliversabove 3 μm particle size (Dv50). The particle size values reduced by atleast a half when jetting panels were added to introduce turbulence.

Vapor Cooling Rate

FIG. 14 shows the high temperature testing results. Larger particlesizes were observed from all 3 pods when the temperature of inlet airincreased from room temperature (23° C.) to 50° C. When the pods wereheated as well, two of the three pods saw even larger particle sizemeasurement results, while pod 2 was unable to be measured due tosignificant amount of leakage.

Without wishing to be bound by theory, the results are in line with theinventors' insight that control over the vapor cooling rate provides animportant degree of control over the particle size of the aerosol. Asreported above, the use of a slow air velocity can have the result ofthe formation of an aerosol with large Dv50. It is considered that thisis due to slower air velocity allowing a slower cooling rate of thevapor.

Another conclusion related to laminar flow can also be explained by acooling rate theory: laminar flow allows slow and gradual mixing betweencold air and hot vapor, which means the vapor can cool down in slowerrate when the airflow is laminar, resulting in larger particle size.

The results in FIG. 14 further validate this cooling rate theory: whenthe inlet air has higher temperature, the temperature difference betweenhot vapor and cold air becomes smaller, which allows the vapor to cooldown at a slower rate, resulting in larger particle size; when the podswere heated as well, this mechanism was exaggerated even more, leadingto an even slower cooling rate and an even larger particle size.

Further Consideration of Vapor Cooling Rate

In this example, the vapor cooling rates for each tube size and flowrate combination were obtained via multiphysics simulation. In FIG. 15and FIG. 16, the particle size measurement results were plotted againstvapor cooling rate to 50° C. and 75° C., respectively.

The data in these graphs indicates that in order to obtain an aerosolwith Dv50 larger than 1 μm, the apparatus should be operable to requiremore than 16 ms for the vapor to cool to 50° C., or an equivalent(simplified to an assumed linear) cooling rate being slower than 10°C./ms. From an alternative viewpoint, in order to obtain an aerosol withDv50 larger than 1 μm, the apparatus should be operable to require morethan 4.5 ms for the vapor to cool to 75° C., or an equivalent(simplified to an assumed linear) cooling rate slower than 30° C./ms.

Furthermore, in order to obtain an aerosol with Dv50 of 2 μm or larger,the apparatus should be operable to require more than 32 ms for thevapor to cool to 50° C., or an equivalent (simplified to an assumedlinear) cooling rate being slower than 5° C./ms. From an alternativeviewpoint, in order to obtain an aerosol with Dv50 of 2 μm or larger,the apparatus should be operable to require more than 13 ms for thevapor to cool to 75° C., or an equivalent (simplified to an assumedlinear) cooling rate slower than 10° C./ms.

Conclusions of Particle Size Examples

In this work, particle size (Dv50) of aerosols generated in a set ofrectangular tubes was studied in order to decouple different factors(flow rate, air velocity, Reynolds number, tube size) affecting aerosolparticle size. It is considered that air velocity is an important factoraffecting particle size—slower air velocity leads to larger particlesize. When air velocity was kept constant, the other factors (flow rate,Reynolds number, tube size) has low influence on particle size.

The role of turbulence was also investigated. It is considered thatlaminar air flow favors generation of large particles, and introducingturbulence deteriorates (reduces) the particle size.

Modelling methods were used to simulate the average air velocity, themaximum air velocity, and the turbulence intensity in the vicinity ofthe wick. A COMSOL model with three coupled physics has also beendeveloped to obtain the vapor cooling rate.

All experimental and modelling results described in these examplessupport a cooling rate theory that slower vapor cooling rate is asignificant factor in ensuring larger particle size. Slower airvelocity, laminar air flow and higher inlet air temperature lead tolarger particle size, because they all allow vapor to cool down atslower rates.

The features disclosed in the foregoing description, or in the followingclaims, or in the accompanying drawings, expressed in their specificforms or in terms of a means for performing the disclosed function, or amethod or process for obtaining the disclosed results, as appropriate,may, separately, or in any combination of such features, be utilized forrealizing the disclosure in diverse forms thereof.

While the disclosure has been described in conjunction with theexemplary embodiments described above, many equivalent modifications andvariations will be apparent to those skilled in the art when given thisdisclosure. Accordingly, the exemplary embodiments of the disclosure setforth above are considered to be illustrative and not limiting. Variouschanges to the described embodiments may be made without departing fromthe spirit and scope of the disclosure.

For the avoidance of any doubt, any theoretical explanations providedherein are provided for the purposes of improving the understanding of areader. The inventors do not wish to be bound by any of thesetheoretical explanations.

Any section headings used herein are for organizational purposes onlyand are not to be construed as limiting the subject matter described.

Throughout this specification, including the claims which follow, unlessthe context requires otherwise, the words “have”, “comprise”, and“include”, and variations such as “having”, “comprises”, “comprising”,and “including” will be understood to imply the inclusion of a statedinteger or step or group of integers or steps but not the exclusion ofany other integer or step or group of integers or steps.

It must be noted that, as used in the specification and the appendedclaims, the singular forms “a,” “an,” and “the” include plural referentsunless the context clearly dictates otherwise. Ranges may be expressedherein as from “about” one particular value, and/or to “about” anotherparticular value. When such a range is expressed, another embodimentincludes from the one particular value and/or to the other particularvalue. Similarly, when values are expressed as approximations, by theuse of the antecedent “about,” it will be understood that the particularvalue forms another embodiment. The term “about” in relation to anumerical value is optional and means, for example, +/−10%.

The words “preferred” and “preferably” are used herein refer toembodiments of the disclosure that may provide certain benefits undersome circumstances. It is to be appreciated, however, that otherembodiments may also be preferred under the same or differentcircumstances. The recitation of one or more preferred embodimentstherefore does not mean or imply that other embodiments are not useful,and is not intended to exclude other embodiments from the scope of thedisclosure, or from the scope of the claims.

1. A smoking substitute apparatus for generating an aerosol, comprising:an aerosol generation chamber containing an aerosol generator beingoperable to generate an aerosol from an aerosol precursor, the aerosolgeneration chamber having a chamber outlet and at least one chamberinlet, air flowing in use from said at least one chamber inlet into theaerosol generation chamber towards the chamber outlet to entraingenerated aerosol for inhalation by a user drawing on the apparatus;wherein, when the apparatus is oriented upright, said at least onechamber inlet is positioned higher than the position of the aerosolgenerator and configured so that substantially all of the airflowentering the aerosol generation chamber is directed away from theaerosol generator.
 2. The smoking substitute apparatus of claim 1,further comprising a housing containing the aerosol generation chamber,wherein one or more electrical contacts are provided on a first end ofthe housing and electrically connected with the aerosol generator, andwherein the one or more electrical contacts are configured to engagewith corresponding electrical terminals on a main body of a smokingsubstitute system.
 3. The smoking substitute apparatus of claim 2,wherein the one or more electrical contacts have an electricallyconductive surface which extends substantially orthogonally to alongitudinal axis of the housing.
 4. The smoking substitute apparatus ofclaim 1, further comprising a housing containing the aerosol generationchamber, wherein one or more electrical contacts are provided on asidewall of the housing and electrically connected with the aerosolgenerator, wherein the one or more electrical contacts are configured toengage with corresponding electrical terminals on a main body of asmoking substitute system.
 5. The smoking substitute apparatus of claim4, wherein the one or more electrical contacts have an electricallyconductive surface which is substantially parallel to a longitudinalaxis of the housing.
 6. The smoking substitute apparatus of claim 2,wherein the one or more electrical contacts are provided on an externalsurface of the housing.
 7. The smoking substitute apparatus of claim 2,wherein the one or more electrical contacts are resiliently movable foreffecting a secure electrical connection with the correspondingelectrical terminals on the main body.
 8. The smoking substituteapparatus of claim 1, wherein, when the apparatus is oriented upright,the aerosol generation chamber is sealed against air flow into or out ofthe chamber in a region level with and below the position of the aerosolgenerator.
 9. The smoking substitute apparatus of claim 1, wherein airflows in use along an air flow path between the chamber inlet and thechamber outlet, and wherein the aerosol generator is arranged to bespaced from the air flow path.
 10. The smoking substitute apparatus ofclaim 1, wherein the aerosol precursor comprises a liquid aerosolprecursor, and wherein the aerosol generator comprises a heaterconfigured to generate the aerosol by vaporizing the liquid aerosolprecursor.
 11. The smoking substitute apparatus of claim 1, wherein thechamber inlet is formed on a sidewall of the aerosol generation chamberat a position in between the aerosol generator and the chamber outlet.12. The smoking substitute apparatus of claim 1, wherein the smokingsubstitute apparatus is configured to generate an aerosol having adroplet size, d₅₀, of at least 1 μm.
 13. A smoking substitute system forgenerating an aerosol, comprising: i) a smoking substitute apparatus forgenerating an aerosol, comprising: an aerosol generation chambercontaining an aerosol generator being operable to generate an aerosolfrom an aerosol precursor, the aerosol generation chamber having achamber outlet and at least one chamber inlet, air flowing in use fromsaid at least one chamber inlet into the aerosol generation chambertowards the chamber outlet to entrain generated aerosol for inhalationby a user drawing on the apparatus; wherein, when the apparatus isoriented upright, said at least one chamber inlet is positioned higherthan the position of the aerosol generator and configured so thatsubstantially all of the airflow entering the aerosol generation chamberis directed away from the aerosol generator; and ii) a main bodyconfigured to engage with the smoking substitute apparatus; wherein themain body comprises a controller and a power source configured toenergize the aerosol generator.
 14. The smoking substitute system ofclaim 13, wherein the smoking substitute apparatus further comprises ahousing containing the aerosol generation chamber, wherein one or moreelectrical contacts are provided on a sidewall of the housing andelectrically connected with the aerosol generator, wherein the one ormore electrical contacts are configured to engage with correspondingelectrical terminals on a main body of a smoking substitute system,wherein the main body comprises corresponding electrical terminalsconfigured to engage with the one or more electrical contacts by asliding fit.
 15. A method of using a smoking substitute apparatus, thesmoking substitute apparatus comprising: an aerosol generation chambercontaining an aerosol generator being operable to generate an aerosolfrom an aerosol precursor, the aerosol generation chamber having achamber outlet and at least one chamber inlet, air flowing in use fromsaid at least one chamber inlet into the aerosol generation chambertowards the chamber outlet to entrain generated aerosol for inhalationby a user drawing on the apparatus; wherein, when the apparatus isoriented upright, said at least one chamber inlet is positioned higherthan the position of the aerosol generator and configured so thatsubstantially all of the airflow entering the aerosol generation chamberis directed away from the aerosol generator, the method comprising: i)generating an aerosol with the aerosol generator; ii) drawing on theapparatus to cause an air flow to enter the aerosol generation chamberand entrain the generated aerosol.